John SLade wrote:

Over in the Canard Community Forum there's a guy from Europe complaining
that his Cozy IV oil runs too cool, even in summer. He's planning a
butterfly valve or closable NACA floor  to close off his scoop. Here's a
picture of the scoop.

Paul Lamar commented:

That is not exactly a NACA scoop. NACA scoops are assumed to be on flat surfaces.
It is interesting never the less. Look's highly configuration sensitive. He may
have stumbled on to something. The hump may help by pass the boundary layer.

Russell Kent wrote:

When I look at this photo, I see *tons* of external diffusion.  The NACA-like "nose"
of this vent may be tripping the boundary layer into the two vortices like a flat
NACA vent does.  The arched lip of the vent captures the vorticies along with the
free-stream air that the voticies are surely dragging around.  But then the severe
restricition inside the vent (what is that, a 70% reduction in cross-section area?)
is going to make all of that air pile up and cause external diffusion.

Maybe Dan can run a CFD on it.

Russell Kent

Don't forget the restriction of the oil cooler itself. BTW you just described
the main problem with NACA ducts.

Paul Lamar
 
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